How To Increase E-Bike Torque

E-bikes are incredible pieces of equipment, but they can also be incredibly expensive. So, it’s always best to do proper research before purchasing. But if you have already bought your bike, and would’ve liked a little more torque, don’t stress. Fortunately, there are a few options to give you a bigger push.

Torque is directly related to amperage, which means that a 5% increase in amps will yield a 5% increase in torque. This relationship means you can get more torque by upgrading your e-bike controller and battery. It’s also possible to get more torque by changing your drive train.

As you can probably guess, messing with your bike’s electronics isn’t risk-free, and there are several limitations that you should be aware of. Also, it’s relatively easy to confuse a concept like torque, which changes drastically depending on your riding speed. This means you must decide if you need extra low-speed or high-speed torque.

Understanding The Relationship Between Torque And Speed

I remember after watching the first Fast and Furious movie how my friends and I would throw around words like “power,” “supercharger,” and “torque” in conversation without having a clue what they meant.

To put it plainly, upgrading your torque isn’t necessarily going to boost your top speed, but it will help you reach that top speed faster. This is because torque is a rotational force. The more torque your bike has, the more it can help you turn the pedals, especially at lower speeds.

But, once you start getting up to speed, your motor’s torque begins to decline.

That said, you may want to upgrade your torque for a few good reasons. While torque doesn’t determine your top speed, it determines how quickly you can get going, how steep your bike can climb, and how much weight you can comfortably pack. This makes more torque especially useful for tourers who pack lots of gear and often traverse rough terrain.

Torque Is Limited In Three Phases

As we have touched on, torque doesn’t stay constant throughout your ride and decreases as your speed increases. There are three phases during which torque is limited in one way or another, meaning that upgrading only one component will only change torque delivery during one phase.

Phase 1 – The Controller Limits Torque At Low RPMs

At low speeds or RPMs, like when pulling away, climbing a steep hill, or just inching along slowly with a heavy load, the torque is maxed out by the amperage limiter in your e-bike’s controller. In other words, your controller determines how much amperage is fed into your motor, determining the torque it can deliver.

So, if you need to increase torque in this low-speed range, one option is to upgrade your controller to deliver more amps. But (and this is a big “but”), be sure to research and ask a professional for advice. Adding amps means adding heat and strain to your motor; if it can’t handle the added amps, it could burn out.

Also, check that your battery can deliver higher amps. Otherwise, you risk spending money on a new controller only to discover that you’ve already maxed out your battery.

Phase 2 – The Battery Limits Torque During Acceleration

The second phase, or range during which torque is limited, is when you gain speed and momentum. During this phase, your battery takes the spotlight, meaning that the limitation is the amperage your battery can feed into the controller.

Obviously, it would help if you upgraded your battery to increase torque in this range. And it’s not uncommon to change both your controller and your battery which will increase torque during the first and second phases.

Phase 3 – The Motor Limits Torque At High Speeds

Suppose you are the kind of rider who wants to spring up hills as fast as possible or have the torque to help you get out of sticky situations on the descents. In that case, you must upgrade the torque at the top speed end.

During this phase, your torque drops off considerably due to your motor. At some point, your motor reaches a point that causes a “back electromagnetic force” or “back EMF.” As your motor increases speed by spinning faster, it also increases resistance.

Think of this like a fighter jet pushing against the sound barrier. The more the plane pushes against the barrier, the more the barrier fights back. In this case, as the resistance in your motor increases, the amperage decreases dramatically, which lowers your torque.

In this case, you need to change your motor. But you may also need to change your battery to deliver higher amps for longer. And for the extra amps to make it to your motor, you probably need to swap out the controller.

On the topic of e-bike motors, it’s also important to know that the position of the motor also affects the amount of torque it delivers. Typically, mid-drive motors directly help you turn the pedals and produce more torque than rear-hub motors.

Change Your Drivetrain To Increase Your Torque

Another relatively simple option to increase the torque output of your e-bike is to change your gearing. For example, a slightly smaller chainring in front will help you put down a bit more torque but will also decrease your top speed.

Alternatively, you can add a bigger low gear (also known as your granny gear) at the back, which won’t affect your top speed, but will help you a lot at the low-speed end or during steep and technical climbs.

The plus side of changing your drive train before your electronics is that you don’t risk any damage to your motor and other expensive components. It could also help improve your fitness because you aren’t expecting a bigger motor to do all the work for you.

Conclusion

Your e-bike’s torque is directly related to the amperage going to the motor, which means you can increase your torque by increasing your amps. At low speeds, amps can be increased by upgrading your controller. During acceleration, you can increase the amperage by upgrading your battery, and, finally, at top speeds, you will need to upgrade your motor and battery for higher amperage.

Author

  • Miles Baxter

    Miles Baxter is an engineer with a longstanding love for bicycles, sparked by winning a mountain bike in a childhood lottery. Balancing a keen interest in mechanics with the thrill of biking, his career is a testament to the art of turning wheels and gears into adventures.

    Baxter Miles